1. Field of the Invention
The present invention relates to a flexible Printed Circuit (PC) board, junction method thereof and a battery pack using the flexible PC board to prevent cracking of terminal units of a flexible PC board and to reduce degradation thereof due to deformation by increasing tensile strength.
2. Description of the Related Art
A flexible PC board refers to a board on which minute circuits are printed on thin films of flexible plastic materials, and which has been developed to service the industrial tendency toward high density, compact size and high functionality in electrical and electronic products.
The flexible PC board is capable of highly dense three-dimensional wiring, higher durability for repeated bending, less wiring degradation, and superior assembly.
Therefore, it has been widely used in cameras, computers, computer peripheral devices, hand-held phones, video/audio devices, camcorders, printers, Thin Film Transistor Liquid Crystal Devices (TFT LCDs), satellite systems and medical equipment, and so on.
The flexible PC board generally has a multi-layer structure wherein wiring of either copper or nickel is formed on a flexible substrate of conductive insulating sheets, such as polyethylene terephthalate (PET) and polyimide (PI), and a coverlay of insulating film for protecting circuits is stacked thereon.
The flexible PC board is capable of electrical connections between separated circuit boards when placed therebetween.
In a case of a hand-held phone with a main body and a folding portion that can be folded and connected by a hinge, the flexible PC board connects a main substrate incorporated in the main body and an auxiliary substrate incorporated in the folding portion for operating an LCD panel therein, so that the main substrate and the auxiliary substrate can both transmit and receive signals to and from each other.
In a case where the flexible PC board is connected to another circuit substrate, as above, wiring terminals of wiring formed in the flexible substrate may be exposed and connected to connecting units of another circuit substrate.
Conventionally, the wiring terminals are exposed by removing some portion corresponding to the wiring terminals to expose both the flexible substrate and the coverlay that are placed on both sides of the center of the wiring.